Gravity actuated tension regulator for drawing presses



May 17, 1932. F. A. SCHAEFER GRAVITY ACTUATED TENSION REGULATOR FOR DRAWING PRESSES Filed Dec. 22, 1928 INVENTOR.

Patented May 17, 1932 I i i I I UNITED STATES PATENT OFFICE FERDINAND IA. SCHAEFER, or BALTIMORE, MARYLAND GRAVITY AO'IUATED TENSION REGULATORFQR DRAWING PRESSES I Application filed December 22, 1928. Serial No. 328,025.

This invention relates to an attachment to the punching and drawing takes place by presses to provide uniformity of initial tenflexing a portion of it adjacent to the portion sion on a blank or strip while being drawn to be punched, taking care to leave the flexed and formed. It enables a number of cups or portion free to be pulled back to its original deep depressions to be made simultaneously plane, by the drawing action of the die or 55 on a single strip, it includes a process for use dies, overcoming the initial tension caused in deep drawing and punching. 7 by the flexing.

Heretofore when metal was drawn in It will be seen that the invention consists presses, rubber pads or springs, or other broadly in regulating the flow of metal to 10 means had to be employed on' the pressure the dies in deep drawing by placing the strip 60 ring or blank holder to iron out the "drawn or blank under constant initial tension by metal and prevent wrinkling or cracking. means of flexingthe strip or blank by exert- Since the pressure of these devices increased ing pressur thereon. The novelty, consists with the compression of the rubber or spring, broadly in substituting such constant initial it was found necessary to employ compentension for frictional resistance. The inas sating attachments, which were both compliventi'on is not limited to any specific form of cated and unsatisfactory. die or blank or manner of supporting the Uniformity in pressure was sought in orblank on the die or pressure means of flexder to insure proper flow of metal in the ing the blank. For instance, any means of drawing operation. But this result could not exerting pressure known to those skilled in 7" be attained because frictional resistance was the art or now used in compensating devices depended on to govern the drawing of the on friction rings may be used for this purmetal. And, as is well known, friction varies pose by applying such pressure means directnot only with the character and condition ly to thesurface ofth'e blanks. Thus any of the surfaces, but with the time they'have such equivalent means of exerting pressure remained in contact and with the speed. to flex the blanks may be substituted for the Moreover, kinetic friction is usually double weights illustrated in the drawings. 1 static friction. So, it is obvious that any I am-thus not only able to dispense with means depending on frictional resistance reliance on frictiornbut I am able to dis-- might be uncertain in its action. There can pense also with the pressure ring formerly so be no uniformity in the flow of metal to a used to regulate the drawing of metal. By die' as long as the flow is governed by fricmy novel use of constant initial tension I tion. am able to regulate accurately as well as in- It is evident that the flow of metal is desure uniformity in the flow ofmetal in deep 35 pendent, not on the constancy of the prespunching and drawing.

sure exerted on the blank, but on the uni- I provide simple gravity actuated means formity of the resistance that blank or strip to take up the slack of the strip or blank and oflers to the drawing action and the strength keep it under the uniform tension desired, 1 of this resistance. It is only when the pull and am thus enabled to use a single acting of the drawing die overcomes the resistance press carrying a number of punchesand dies offered to such pull by. the blank or strip, to form and draw simultaneously in one opthat there can be any flow of metal. The eration on a single strip the desired number accurate regulation of this resistance and its of cups or depressions. uniformity is the crux of the problem. By my invention the limitations and dis- I obtain the desired uniformity in the readvantages due to the use of friction rings or as sistance the blank or strip'ofl'ers to the drawother customary means of regulating the flow ing action of the die by entirely eliminating of metal to dies are avoided and the drawfrictional'resistance and substituting thereing of metal accurately regulated by the 1 ,for what I term constant initial tension. I amount'of flexing which governs the con- 7 place the blank or strip under tension'before stant'initial tension of the blank or strip. 1 0' Th flexing can be accurately regulated by the pressure exerted on the portion of the blank to be flexed. After clamping the flexed blank or strip in adjusted position in relation tothe die or dies, as soon as the drawing action overcomes the resistance offered by. the constant initial tension of the blank, metal is drawn from the flexed portion andthe flexure correspondingly decreased.

In the drawings illustrating one embodi ment of my invention Fig. 1 is a side elemtion view of the punch bed and attachments. Fig. 2 is a plan viewof the same looking P- A Fig. 3 is a side elevation view of the die beds and attachments. 7V V I ,Fig. 4 is a plan view of the same looking down.

Fig. 5 is an end elevationview of the punch bed and attachments.

Figs. 6, 7 and 8 are parts of a die.

The punch bed punches l which are riveted to the block or bolster 2. The stud 5 connectsthe punch detailed views of: the

bed to the ram of the press (not show-11).,

The two spindles 6 carrying the Weight .7 move vertically in their hearings on the punch bed 3. The shearing punches8 at the two ends of the punch bed cut the strip to. the desired length, andserve to hold the sheared strip as flexed in adjusted position in relation to the punch and die. The punch block 2 is fastened to the bed 3 by thescrews 4.

The die bed 11 carries the three dies 9 which are riveted to the block or bolster 10 which is screwed on to the'die bed. These dies are made in three parts of different lengths as shown in Figs. 6,7 and 8, the smaller fitting in and being riveted to the larger. p p V The strip can be automatically fed into the press with sufficient slack te enable three cups to be drawn on the strip. Thesl'ack is taken up by the pressure of the spindles which depress the strip at thepoints of contact, until the drawing action of the punches takesup the slack, causing the weights to rise. Thus the tension on the strip is kept constant as the weights lift and the strip is sheared at.

is lowered, with the underlying portion of the strip lying midway between the dies,

pressing down on such portion and flexing;

3 is provided with the three lto 5 of the drawings.

the strip until the resistance of the strip balances the pressure or the lowest point of fiexure takes up against the die bed 11. The amount of this flexure can be accurately controlled by the resiliency of the strip, the weight and the height of the face of the die above the top of the die bed.

The shearing edges of the end punches 1 cut the flexed strip to the desired length, as the punches register with the dies, gripping the flexedstripin adjusted set position and by overcoming initial tension of the strip draw themetal;

Preferably a flat thin resilient blank or strip is used so anyone susceptible of flexing can be employed in my-invention. It is essential that theblank,bemounted on the die.

so that it can freely flex on the application of pressure onits surface; Then by,clamping the strip or blank beyond the flexedpor- 7 tion the constant initial resistance caused by the flexure willregul-ate the flow of metal. This means of keeping the strip to be punched and drawn under constant pressure can be utilized wherever it is desiredto form,

on a single strip a number of cups or depressions requiring drawing the material of the strip,

My invention. can alsobe utilized on a 1 singleblank and punch and die, by having the weights press down onthe free edges ofthe blank, as is shown by dispensing with the end punches and diesrshown in the Figures Nor is my invention limited to weights opblank." Obviously the pressure on the edges of the blankcould be exerted by any weight or other equivalent means of exerting pressure. suitably controlled, exerting either downwards or upwards pressure on theportion vofthe blank. All that is essential for:

punching-a plurality of cup-like depressions .on 'a strip, is that aportion of the blank be suificiently displaced or temporarily deformed upwards or downwards from'the flat surface ef the blank to provide enough slack erated on spindles bearing downward on the metal to enable such portion to provide necessary metal for the drawing operation, the moment the pull of the drawing operation overcomes the pressure exerted by the gravity actuated means. The tension can be regulated and varied as well as the amount o fslack metal-taken up to suit the special needs, byv

regulating the size ofthe weights or other equivalent means of exerting pressure, and

thedistance the blank or strip can be displaced, before it takesup against the die or punch bed. I

I claim:

1. The combination for simultaneously stamping and drawing :on a s1ngle.a'cti ng pressa pluralityrof depressions on'an integralstrip of sheet metal, said combination comprising of a plurality of drawing punches .130

and a corresponding number of drawing dies, the punches and dies being adapted and positioned on their respective holders to register with each other and one or more gravity actuated means intermediate each pair of punches or dies for maintaining the strip at a uniform tension during the stamping and drawing process.

2. A multiple punch and die for simultaneously stamping and drawing the end and middle portions of an integral strip of sheet metal, comprising of two shearing and drawing punch and die members and midway thereon a third drawing punch and die member and a gravity actuated means intermediate each pair of punch and die members for maintaining the strip at a uniform tension during the stamping and drawing process.

3. A multiple punch and die for simultaneously stamping and drawing the end and middle portions of an integral strip of sheet metal comprising of two registering, shearing and drawing punch and die members and midway on the strip a third registering, drawing and punch member and a gravity actuated member intermediate each punch member, said member consisting of a weight, a spindle carrying the weight, slidably mounted on a punch holder, the end of the spindle pressing and supported on the strip of metal, whereby the strip is kept under uniform pressure during the stamping and drawing process.

4. A method of drawing and deeply punching aflat sheet metal blank in one operation on a drawing press, consisting in first exerting pressure by gravity actuated means on a portion capable of vertical movement of the blank lying in adjusted position on a die bed, whereby such portion is displaced or temporarily deformed, then subjecting another portion of the blank to the drawing and punching operation, whereby the displaced portion can supply suflicient slack metal for the drawing process, while the blank is continually held under uniform tension by the constant pressure of the gravity actuated means.

5. A method of regulating the drawing of metal in deep punching by subjecting the blank to uniform tension comprising flexing a portion of the blank adjacent to the portion to be punched to perpendicular pressure exerted by gravity means, then securing the flexed blank in adjusted position for the action of the die whereby the drawing action must overcome the uniform initial tension before there is any flow of metal.

6. The process of drawing metal without utilizing frictional resistance comprising slightly flexing by pressure a portion of the blank, clamping the blank so flexed in set position for drawing and punching whereby the flexure is maintained and the blank kept under uniform predetermined initial tension by thepull exerted by the fiexure, thensubj ecting the blankto theaction of the punch, drawing metal from the flexed portion as soon as'the drawing action overcomes the uniforminit-ial tension, whereby the metal required to supply the deep drawing is drawn.

prising flexing by gravity means, the central portion of the blank, a predetermined amount, then clamping the margin of the ticked blank, then subjecting a portion of the blank lying in approximately the original plane of the-blank, to the punching and drawing action whereby the ipressure of the gravity means is overcome, and theflexed portion is drawn toward the punch portion, supplyinga flow of extra metal to the die.-

9. The process of drawing and deeply stamping a section. of a fiat metallic blank, lying horizontally on the face of a die, con sisting inticking the section of the blank by direct downward pressure of a weight free to move vertically, then clamping the flexed blank in set position, whereby the blank remains under constant predetermined tension, then subjecting the blank to the drawing action of the stamping.

10. The process of drawing and punching a blank having a flat central portion and slightly curved, resilient marginal portions comprising resting the flat portion on the face of a die, projecting from the die bed, clampingthe edges of the portion so curved in set position on the press, so that the edges rest in the plane of the die, and the fiat portion lies in adjusted position in relation to the punch and die, then subjecting the flat portion of the blank, to the punching action of the die, whereby its drawing action is governed by the resistance offered by the curved portion to straightening.

11. The method of regulating the drawing of metals in deep punching and stamping by means of placing the surplus metal under uniform initial tension, which method comprises flexing by perpendicular pressure on its surface a portion of a flat blank by gravity means, free to move vertically, then securing the flexed blank in set adjusted position, for deep punching and drawing, whereby the drawing pull of the punch must overcome the constant contrary tension of the blank,

and the resistance offered by the gravity means to any decrease in flexure, before ther is any flow of metal. a y 12. The process of punching and drawing a plurality of deep cups ona metal strip comprising resting the strip on the face of Va plu-' I rality of spaced dies, then, by exerting pressure perpendicular thereto, flexing the strip intermediate the-dies, then performing the fl draw'ing and cupping, whereby the drawingpull; exerted by the dies overcomes the pressure'on the strips and metal isdrawn tothe dies; 1

13. In a drawing pressprovided with a die v and punch, means ofsupporting the securing on the press a flat slack blank in adjusted position, whereby a portion of the blank is left free to move perpendicularly to its plane, and pressure means for moving the free por- Qgtion of the blank perpendicularly'to form a curved portion, whereby the slack of the blank is taken up and the blank kept under 1 constant initial tension;

14. In a press provided with a die and h punch for deep punching, means for support- 7 ing in its plane a portion of a flat resilient blank, 'gravity means for flexing an unsecured portion, of the blank, together with means for clamping the flexed blank in set rposition in relation to-the punch and die, whereby the blank is kept under constant tension until such tension is overcome the drawing action.

15. A method of regulating the flow of ma- .11611211 from a flexible blank to a drawing press comprising supporting the blank in adjusted position for the drawing operation so that the blank contacts'only with a face of the'die or punch, and with an outlyingportion of maths drawing press, then flexing by pressure means the unsupported portion of the blank adjacent the die, then clamping the outlying contact of the blank, before subjecting it to the drawing action of the die. 5;; In testimony whereof I'aflix my signature.

- FERDINAND A. SCHAEFER.

CERTIFICATE or CORRECTION.

?atentNo. 1,858,463. May 11, 1932.

FERDINAND A. SGHAEFER.

it is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, line 130, claim 1, strike out the word "of" first occurrence; page 3, lines 12 and 22, claims 2 and 3, respectively, after the word "comprisng" strike out the word "of"; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 4th day of October, A. D. 1932.

M. J. Moore, (Seal) Acting fiommissioner of Patents. 

